1. Technical Field
The present invention relates to machine tool rotary cutting tools in general, and to end mills in particular.
2. Background Information
An end mill is an example of a rotary cutting tool that is used to remove material from a workpiece. Conventional end mills typically include a shank section and a fluted section. The fluted section typically includes a plurality of helical teeth, each tooth having a cutting surface and a relief wall. It is desirable to have an end mill that can rapidly remove material from a workpiece, while at the same time leave a relatively smooth surface on the workpiece. To that end, there are a variety of different end mill designs. U.S. Pat. No. 4,560,308 discloses an end mill with a plurality of helical teeth each with a sinusoidal edge that facilitates chip formation and removal. The '308 patent also discloses that the sinusoidal pattern is the same for each helical tooth, although the sinusoidal patterns may be axially offset from one another relative to the end of the end mill; e.g., the sinusoidal pattern for a first helical tooth begins at the tip of the mill; the sinusoidal pattern for a second helical tooth, that rotationally follows the first helical tooth, begins at a point located a distance “x” apart from the tip; and the sinusoidal pattern for a third helical tooth, that rotationally follows the second helical tooth, begins at a point located a distance “2x” apart from the tip, etc.
Rotary cutting tools are often subject to periodic forces as cutting edges repeatedly engage with the workpiece. The aforesaid forces can lead to undesirable harmonic responses (e.g., noise, chatter), particularly if the periodic forces are substantially uniform. A substantial harmonic response can limit the performance of the rotary cutting tool, including the finish produced by the tool.
Modern machining centers often utilize greater horsepower than older machining centers and very often include computer controls. The additional power and computer control enables the machining center to employ faster feed rates, provided the rotary cutting tool utilized by the machining center can accommodate the greater forces associated therewith.
What is needed, therefore, is a rotary cutting tool that has improved characteristics relative to the prior art rotary cutting tools currently available, and one that can accommodate the forces associated with higher than conventional feed rates without a detrimental harmonic response.